Messages in this thread | | | Date | Thu, 20 Oct 2005 06:05:01 -0400 (EDT) | From | Steven Rostedt <> | Subject | Re: Ktimer / -rt9 (+custom) monotonic_clock going backwards. |
| |
On Thu, 20 Oct 2005, Steven Rostedt wrote:
> > On Thu, 20 Oct 2005, Ingo Molnar wrote: > > > > > * Steven Rostedt <rostedt@goodmis.org> wrote: > > > > > static inline nsec_t __get_nsec_offset(void) > > > { > > > cycle_t cycle_now, cycle_delta; > > > nsec_t ns_offset; > > > > > > /* read clocksource */ > > > cycle_now = read_clocksource(clock); > > > > > > /* calculate the delta since the last timeofday_periodic_hook */ > > > cycle_delta = (cycle_now - cycle_last) & clock->mask; > > > > > > /* convert to nanoseconds */ > > > ns_offset = cyc2ns(clock, ntp_adj, cycle_delta); > > > > > > /* Special case for jiffies tick/offset based systems > > > * add arch specific offset > > > */ > > > ns_offset += arch_getoffset(); > > > > > > return ns_offset; > > > } > > > > > > cycle_now is 32 bits. If the clocksource overflows (which it can in > > > 30 seconds) the cyclec_delta will be wrong. > > > > isnt cycle_t 64 bits? > > > > Not anymore. > > include/linux/time.h: > > /* timeofday base types */ > typedef s64 nsec_t; > typedef unsigned long cycle_t; >
FYI,
I just switched cycle_t to u64 and hackbench no longer makes the time go backwards.
John, would this cause any problems to keep cycle_t at s64?
-- Steve - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |